How can I do a load test on Lifepo4 310ah of 250 watts

[elvis_asaftei]

Can anyone help with a suggestion?
All batteries have voltage but many can not even sustain 250Watts load test ? ( around 0.2C of 310ah battery)

good battery load voltage :

Bad battery rated at grade A but seller lie :


How can I do a load test like that without having the DC Load Test equipment?

 

[Diysolar123]

you can get a cheap constant current discharge tester...something like:

Digital Voltmeter Car Battery Capacity Tester Constant Current Discharge Meter | eBay

Find many great new & used options and get the best deals for Digital Voltmeter Car Battery Capacity Tester Constant Current Discharge Meter at the best online prices at eBay! Free shipping for many products!

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and just do a full capacity test and there is your answer.

 

[elvis_asaftei]

you can get a cheap constant current discharge tester...something like:

Digital Voltmeter Car Battery Capacity Tester Constant Current Discharge Meter | eBay

Find many great new & used options and get the best deals for Digital Voltmeter Car Battery Capacity Tester Constant Current Discharge Meter at the best online prices at eBay! Free shipping for many products!

www.ebay.com

and just do a full capacity test and there is your answer.

I specified I want to do a Load Test and not Capacity Test . do you know the difference? Usually all batteries that pass the load test will also pass the capacity test but not otherwise.

 

[elvis_asaftei]

you can get a cheap constant current discharge tester...something like:

Digital Voltmeter Car Battery Capacity Tester Constant Current Discharge Meter | eBay

Find many great new & used options and get the best deals for Digital Voltmeter Car Battery Capacity Tester Constant Current Discharge Meter at the best online prices at eBay! Free shipping for many products!

www.ebay.com

and just do a full capacity test and there is your answer.

See the 2 images from above . Voltage drop is what is happening with bad battery at the same 250 watts one is 1 volt and the other steady 3 volts

 

[Wibla]

So buy a load tester? or rent one? maybe a nearby university has an electronics lab that will let you use/borrow one?

do you know the difference?

Why do I get such a bad vibe from this statement? Your attitude (as perceived) will do you no favors, it'll only serve to highlight to other forum users, who use their own precious free time to help others, that your posts should be ignored.

 

[Diysolar123]

I specified I want to do a Load Test and not Capacity Test . do you know the difference? Usually all batteries that pass the load test will also pass the capacity test but not otherwise.

well lets try and help you in spite of yourself.
fyi, yes, I know the difference; your question was presented in such a fashion that it was from someone who was not sure what they were really asking about.

what exactly is the spec of the battery suppose to be? You have not said at all...
Not all batteries have the same charge/discharge specs.
I suspect you have a low C rate battery because its a 310Ah cell, as the capacity goes up you often have a significant drop in max C rate.
what is the internal resistance "suppose" to be??
Do you have an battery resistance test meter?, that is a simple piece of test equipment.
Was your battery fully charged at the start of the test?

do a capacity test to make sure you know what you have as your vendor has probably specified a capacity, but did they call out a discharge rate?
There is no mystery to trying to pull a full load test, the load is just a resistor; in this case a resistor that can dissipate a lot of heat.
You want to pull a 0.5C load test; lets do the math...

310 * 0.5 = is going to be a 155amps.
with a cell voltage of 3.4 (lets pretend you know to charge your cells first) you will want a resistor bank of around:
3.4 / 155 = 0.022 ohms or around 22 mohms (your battery internal resistance should be much less than a milliohm)
(fyi, this is around five 0.1ohm power resistors in parallel, they cost about $2 each )

the power your resistor bank will need to handle is 155^2 * 0.022 = 528watts so make sure you get at least 100W rated resistors and plan for cooling, this will very quickly get hot and unsafe! actually this much current is definitely unsafe...better make sure you have a DC rated switch that can safely interrupt that much current.

a milliohm meter will run you around $100 if you want to create an accurate load bank from heavy copper wire
a portable battery internal resistance meter will run you around $70.

 

[time2roll]

What was the resting voltage before that tester was connected? Had you run the cell up to 3.65 volts before the test?
The test should stop at 2.5 volts regardless of the result.

 

[elvis_asaftei]

well lets try and help you in spite of yourself.
fyi, yes, I know the difference; your question was presented in such a fashion that it was from someone who was not sure what they were really asking about.

what exactly is the spec of the battery suppose to be? You have not said at all...
Not all batteries have the same charge/discharge specs.
I suspect you have a low C rate battery because its a 310Ah cell, as the capacity goes up you often have a significant drop in max C rate.
what is the internal resistance "suppose" to be??
Do you have an battery resistance test meter?, that is a simple piece of test equipment.
Was your battery fully charged at the start of the test?

do a capacity test to make sure you know what you have as your vendor has probably specified a capacity, but did they call out a discharge rate?
There is no mystery to trying to pull a full load test, the load is just a resistor; in this case a resistor that can dissipate a lot of heat.
You want to pull a 0.5C load test; lets do the math...

310 * 0.5 = is going to be a 155amps.
with a cell voltage of 3.4 (lets pretend you know to charge your cells first) you will want a resistor bank of around:
3.4 / 155 = 0.022 ohms or around 22 mohms (your battery internal resistance should be much less than a milliohm)
(fyi, this is around five 0.1ohm power resistors in parallel, they cost about $2 each )

the power your resistor bank will need to handle is 155^2 * 0.022 = 528watts so make sure you get at least 100W rated resistors and plan for cooling, this will very quickly get hot and unsafe! actually this much current is definitely unsafe...better make sure you have a DC rated switch that can safely interrupt that much current.

a milliohm meter will run you around $100 if you want to create an accurate load bank from heavy copper wire
a portable battery internal resistance meter will run you around $70.

Batteries are pretending to be 310ah CATL grade A . I have internal resistance tester and resistance is between 0.25mOhms and 0.35mOhms . All batteries was transported by train and stays horizontally and in metalic container that could have exceeded 100C during transport with train in China Desert from Shenzhen to European Battery is rated at 1C discharge and 0.5C charge rate and 4000 cycles and was bought from here :

US $630.50 35％ Off | PWOD 4-16PCS CATL 3.2V 310AH grade A lifepo4 battery RV 320AH battery pack RV and Solar Energy storage system EU US tax free

824.7US $ 35% OFF|Pwod 4-16pcs Catl 3.2v 310ah Grade A Lifepo4 Battery Rv 320ah Battery Pack Rv And Solar Energy Storage System Eu Us Tax Free - Rechargeable Batteries - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

what happens if :
1. battery temperature in metalic container by train will exceed 100Celsius ( is this possible with train in really got sunlight ?) and I think this is not happening by sea because of low temp and container stacking ?
2. Transporting the batteries horizontally and not vertically has any damaging effect ? I notice that when I take them from the transportation box I hear a liquid pouring inside when I put them vertically.

 

[elvis_asaftei]

anyone knows about this situation ?

Batteries are pretending to be 310ah CATL grade A . I have internal resistance tester and resistance is between 0.25mOhms and 0.35mOhms . All batteries was transported by train and stays horizontally and in metalic container that could have exceeded 100C during transport with train in China Desert from Shenzhen to European Battery is rated at 1C discharge and 0.5C charge rate and 4000 cycles and was bought from here :

US $630.50 35％ Off | PWOD 4-16PCS CATL 3.2V 310AH grade A lifepo4 battery RV 320AH battery pack RV and Solar Energy storage system EU US tax free

824.7US $ 35% OFF|Pwod 4-16pcs Catl 3.2v 310ah Grade A Lifepo4 Battery Rv 320ah Battery Pack Rv And Solar Energy Storage System Eu Us Tax Free - Rechargeable Batteries - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

what happens if :
1. battery temperature in metalic container by train shipping will exceed 100Celsius - specifications say maximum 60C !!! ( is this possible with train in really got sunlight ?) and I think this is not happening by sea because of low temp and container stacking ?
2. Transporting the batteries horizontally and not vertically has any damaging effect ? I notice that when I take them from the transportation box I hear the electrolyte liquid pouring inside when I put them vertically.